Dialog resources are facilities permitting operator/machine communication. In multi-tasking word or data processing work stations, they are allocated to tasks (processes) for longer time relative to other resources such as the microprocessor, DASD, and the like. Examples of microcomputer controlled work stations with dialog resources abound. Corwin, U.S. Pat. No. 4,247,906, issued Jan. 27, 1981 and IBM 6580 DISPLAYWRITER illustrate word processing while the IBM 3277 typifies data processing. Relatedly, there are differences in the functions performed by the work station types. For example, the IBM 3277 is a data processing work station exemplified by remote tasking at a host and an interactive relation between the host and terminal. In contrast, the IBM 6580 DISPLAYWRITER executes stand-alone local tasking with only an occasional remote transmission to a host.
An operator key entering a text on a word processor (IBM 6580) and desiring a name and address reference is presently required to suspend entry at the DISPLAYWRITER and invoke data base access by way of the separate keyboard and display of the 3277. To facilitate both remote and local tasking using a single terminal, it is well appreciated within the art to emulate a remote communicating terminal such as the 3277 on the same microprocessor that supports word processing. Indeed, operating systems that give the appearance of executing asynchronous tasks concurrently are well described in U.S. Pat. No. 4,435,780 issued Mar. 6, 1984, to Harrington, et al, entitled "Dispatching Multiple Processes" and Harrington, U.S. Ser. No. 208,621, filed Nov. 20, 1980, entitled "Queuing of Work Requests to Independent Tasks". What is absent from the art is a teaching of an operating system technique to effectuate real time switching of resources among multiple tasks without interference in the execution of any single task. Louie, U.S. Pat. No. 4,152,761, discloses a digital processor programmed to perform multi-tasks which includes a hardware dispatcher for selecting tasks. The dispatcher receives the plurality of dispatcher requests, determines the highest priority request and selects the appropriate program routine. Louie teaches the binding of active tasks for purposes of task switching on a CPU demand basis. The link list represents a queue of active tasks that are sharing the CPU resource, but it has no relationship to task switching at the demand of the user.